1. Field of the Invention
The present invention relates to a method of detecting breakage or disruption of a continuous bead of fluid material during the discharge thereof from an applicator nozzle.
The fluid material utilizable in the practice of the present invention includes, for example, a viscous bonding agent, a viscous coating material, a sealing material or any other viscous material desired to be applied to a work by the use of an applicator nozzle which forms a continuous bead of such material as the latter is discharged from the applicator nozzle.
2. Description of the Prior Art
When it comes to the application of a fluid material, for example, a sealing material, to a work with the use of an applicator of a type having a nozzle, it is a general practice to supply the sealing material under pressure from a storage tank or reservoir towards the nozzle by means of a pump so that a stream of sealing material discharged from the nozzle can eventually form a continuous bead of sealing material on the work. In a certain application, the applicator nozzle is driven along a predetermined path by a computer-assisted manipulator to apply the continuous bead of sealing material to the work so as to fill up a gap having a substantial length. In another application, the applicator nozzle may be manually moved along the predetermined path conforming to the length of the gap in the work.
As the sealing material is consumed for the actual application to the work, the amount of sealing material within the storage tank decreases quite naturally and, in such case, the storage tank has to be replenished with an amount of sealing material. Depending on the type of sealant supply system including the storage tank, the nozzle and a supply tubing leading from the storage tank to the nozzle via the pump, it is often experienced that the failure to remove gases from the pumping system when the storage tank is to be replenished may result in an intrusion of air into the sealing material being pumped through the supply tubing towards the applicator nozzle. This problem may also occur even when the pump is driven when and after the storage tank has been emptied.
When air intrudes into the sealing material being supplied under pressure, the air is compressed within the system together with the sealing material being supplied under pressure while forming air bubbles and, subsequently, expands with the air bubbles consequently ruptured as the sealing material is discharged from the applicator nozzle. This phenomenon tends to bring about a problem in that the sealing material being discharged from the applicator nozzle is discontinued, resulting in a disruption or breakage of a continuous bead of sealing material being deposited on, or otherwise applied to, the work.
The breakage of the continuous bead of sealing material hampers accomplishment of an objective desired of applying the sealing material, or any other fluid material, resulting in a defective sealing or bonding which in turn results in the production of the work which is generally deemed defective.
No attempt has hitherto been made to minimize the above discussed problems by the detection of an occurrence of the breakage or disruption of the continuous bead of fluid material discharged from the applicator nozzle. Therefore, the occurrence of the breakage or disruption of the bead of fluid material emerging from the applicator nozzle has imposed a limitation on the quality of the work to which the fluid material has been applied, coated or otherwise deposited, and/or the yield of the works. It has also constituted a cause of reduction in reliability of automatic application, coating or deposition performed by the computer-assisted manipulator or robot.